Ectotherm
Ectotherm explained in an easy to understand way:
Imagine trying to keep your house comfortable when your thermostat can only be adjusted based on the outside weather. Just like your home would be at the mercy of external temperatures, an ectotherm's body temperature relies entirely on its surrounding environment. In this analogy, your house represents the ectotherm, and the external weather conditions are analogous to the environmental factors that determine the animal's body temperature.
Practice Version
Ectotherm: An animal whose body temperature depends on its environment. Ectotherm. An ectotherm is an animal that relies on external environmental conditions to regulate its body temperature.